1. Field of the Invention
A reelable flow stopper for plugging fluid flow within a pipe, the flow stopper feeds a stopper tape through a hole in a pipe wall and forms a coiled or wound stopper tape which acts as a plug by spanning the inside diameter of a pipe.
2. Description of the Prior Art
Utility services, particularly gas utilities, often require a device which can be inserted into any main or branch pipeline in a distribution system, temporarily stopping the flow of gas in such main or branch pipeline following a procedure commonly known as a "no-blow" or "hot-tap" operation. Heavy construction and earth-moving equipment can damage or rupture a gas main and thereby create an urgent need to quickly and safely stop the gas flow. Existing rapid flow shutdown devices or line stopping equipment do not combine access through a small hole having a diameter approximately equal to 25 percent of the nominal diameter of a pipe, with reusability and sufficient mass and density to work in medium to high pressure systems.
Rapid flow shutdown systems using inflatable cartridges or bladders can be inserted through a relatively small access hole. However, such rapid flow shutdown systems operate successfully only in lower pressure systems, those operating at pressures less than approximately 5 psig, not medium or high pressure systems, those operating at pressures up to approximately 120 psig. A bladder or cartridge small enough to fit into an access hole having a diameter equal to approximately 25 percent of the nominal pipe diameter requires stretching the elastomeric bladder or cartridge beyond safe limits to attain a proper seal. Thus failures of such rapid flow shutdown system due to creep or cold flow can happen rather quickly. A catastrophic failure of the bladder or cartridge would result in almost full fluid flow since the bladder or cartridge has relatively little mass and great volume. Thus in a failed situation, a bladder or cartridge does not impede fluid flow but rather creates a potentially hazardous situation to a working crew at or near a repair trench, the public and property. A flow stopper according to this invention has significantly greater mass than that of a bladder or cartridge flow stopper. Even in a failed situation, because of its mass a flow stopper according to this invention can still substantially reduce the fluid flow in a pipe.
McGowan et al, U.S. Pat. No. 4,295,494 teaches a method and apparatus for plugging and cutting an underground pipeline without any need for excavating to obtain access to the point of plugging. A thermally stabilized cross-linked preshrunk polyolefin plug is inserted into a pipeline from a point where the pipeline exits the earth. The plug is inserted on the end of a heater element, the heater element heats the plug and causes the plug to expand and fit tightly inside the pipeline at or near the main pipeline. Once the plug is expanded into a tight fit, the heater element can be withdrawn from the pipeline. The teachings of the U.S. Pat. No. 4,295,494 reduce the cost of plugging a pipeline since the preshrunk polyolefin plug can be inserted into the pipeline from the point where the pipeline exits the earth and requires no excavating, backfilling and/or repaving.
Garmong, U.S. Pat. No. 4,441,561 teaches a method and apparatus for locating, isolating and treating a section of a formation within a well bore. The formation is isolated within the well bore by using radially expandable packer elements of a straddle packer assembly which are independently expanded and contracted with the application of positive expanding and contracting forces. Such expanding and contracting forces are applied using remotely located controls above ground. The expanding and contracting forces are used to open a partially closed area of a well bore.
Shonrock et al, U.S. Pat. No. 4,554,973 teaches a method and apparatus for sealing a well casing. The U.S. Pat. No. 4,554,973 describes a method for sealing a length of well casing to prevent fluid disposed therein from flowing upwardly into another length of well casing.
Harrison, U.S. Pat. No. 4,607,469 teaches a method and apparatus for sealing tubular conduits carrying utility lines which do not totally displace the void within the tubular conduit. A plurality of dams are spaced within the conduit along the axis of the conduit. A silicone or RTV rubber is injected into a cell and the silicone or RTV rubber is exposed to enough moisture to cure the resin.
Yie et al, U.S. Pat. No. 4,458,721 teaches a pipeline flow restrictor having a plurality of restrictor arms extending from one or both ends of a flow restrictor cartridge. The ends of the restrictor arms, located opposite from the ends of the restrictor arms attached to the flow restrictor cartridge, restrict the inflation of an inflatable sleeve. The inflatable sleeve can be pressurized to fluid pressures greater than the pressure within the pipeline. An inflatable sleeve having restrictor arms according to the U.S. Pat. No. 4,458,721 can restrict flow in pipelines having pressures of up to approximately 125 psig. The U.S. Pat. No. 4,458,721 further discloses a combination boring-insertion tool which utilizes fluid pressure to provide force for the hole cutter.